what i can't understand is if someone like nasa or similar had seen this metereo approcing, or we are completely unaware of some dangerus-but-not-too-big meter
I read the blast was estimated at 500 kt, at an altitude of 10-15 miles. That's huge! I'm surprised it didn't do more damage. Good thing it wasn't closer in.
more are coming
Quote from: lesto on Feb 19, 2013, 06:10 pmwhat i can't understand is if someone like nasa or similar had seen this metereo approcing, or we are completely unaware of some dangerus-but-not-too-big meterHow wide is the sky and beyond, out past the Moon orbit? How small is a 1km rock at 500,000km? Now how small is a less than 20m rock? At relative speeds of asteroid and Earth you need to find the asteroid(s) and determine if/where any might hit the sky in enough time to give meaningful warning, more than just "Everybody duck!" which really means get your cameras out. A 17m rock didn't get noticed until 32 seconds(?) before it exploded. Then it got noticed. That was the warning but who knew what to do? Maybe people knowing more what they see and take action to get under cover is sooner possible? That rock could have killed most everyone in the open for many km around just from the blast had it come much lower. I think of these rocks and the ones going by as missed resources. I won't say they'd be used wisely (more likely be used to take war to a new level) but there they are.
i can understand Radar in space will not work,
Quotei can understand Radar in space will not work, Radar works just fine from earth to space.
However the size of the return signature is related to both the distance and size of the object, so it's a sensitivity issue. The most sensitive method of detected far off and small space objects is photographs taken over multiple days looking at an identical part of space. Any object that has 'moved' relative to the background starts will appear as a streak and is easily to identify, track, and predict it's path thereafter. However there is a lot of space to look at and a finite number of picture takers so smaller objects are always subject to arriving without notice.Lefty
The Vienna, Austria-based Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) runs the International Monitoring System made up of infrasound stations. Infrasound is low frequency sound with a range of less than 10 Hertz. Humans cannot hear the low frequency waves that were emitted by the meteor blast over Russia on Friday (Feb. 15), but they were recorded by the CTBTO's network of sensors as they travelled across continents.